1. Field of the Invention
The present invention relates to an ignition key device including an ignition key for use with a motor vehicle, the ignition key having means for remotely locking and unlocking a door of the motor vehicle and monitoring a status of the motor vehicle.
2. Description of the Prior Art
There has heretofore been known an ignition key device which comprises an ignition key to be inserted into an ignition switch of a motor vehicle and a remote door lock operating unit for remotely locking and unlocking a door of the motor vehicle, the ignition key and the device unit being integral with each other, as disclosed in Japanese patent publication No. 5-85388, for example.
The above publication also reveals an ignition key device comprising an ignition key and a remote door lock operating unit which are separate from each other and electrically connected to each other by two leads.
FIGS. 11 through 13 of the accompanying drawings show respective conventional ignition key devices 1, 11, 21 disclosed in the above publication. In FIGS. 11 through 13, corresponding parts of the conventional ignition key devices 1, 11, 21 are denoted by identical reference numerals.
The ignition key device 1 shown in FIG. 11 houses an electric circuit, which is schematically illustrated, including a diode bridge 2, a chargeable secondary cell 3, and a transmitter 4. The diode bridge 2 has input terminals connected to charging terminals 5, 6, respectively, and output terminals connected across the chargeable secondary cell 3 to the transmitter 4. The transmitter 4 is connected to a push-button switch 7 for locking and unlocking a door, and an antenna 8. The ignition key device 1 has a serrated portion 9 on one or both side edges thereof for performing a key function, i.e., turning on and off an ignition switch.
When the ignition key device 1 is inserted into the slot of an ignition switch lock (not shown) of a motor vehicle in the direction indicated by the arrow until the serrated portion 9 is placed in the slot of the ignition switch lock, a direct current flows from power supply terminals (not shown) that are positioned in the slot and connected to a battery on the motor vehicle to the ignition key device 1 through the charging terminals 5, 6. The direct current is supplied to charge the secondary cell 3 through the diode bridge 2.
When the ignition key device 1 is pulled out of the slot of the ignition switch, the transmitter 4 which is energized by the secondary cell 3 is armed.
When the push-button switch 7 is pressed while the transmitter 4 is armed, the transmitter 4 is operated to transmit a signal from the antenna 8 to a receiver on the motor vehicle. When the receiver on the motor vehicle receives the transmitted signal, a door of the motor vehicle is remotely locked or unlocked.
The ignition key device 11 shown in FIG. 12 comprises an ignition key 12 and a remote door lock operating unit 13 which are separate from each other and electrically and mechanically connected to each other by two insulated or protected leads 14. The ignition key 12 houses charging terminals 5, 6 and a diode bridge 2. FIG. 12 shows a detailed circuit of the diode bridge 2, which is identical to the diode bridge 2 shown in FIG. 11. The unit 13 accommodates a secondary cell 3 and a transmitter 4. The secondary cell 3 can be charged when a serrated portion 9 of the ignition key 12 is inserted into the slot of an ignition switch (not shown) of a motor vehicle.
The ignition key device 21 shown in FIG. 13 comprises an ignition key 22 and a remote door lock operating unit 23 which are separate from each other and electrically and mechanically connected to each other by two insulated or protected leads 14. The ignition key 22 houses charging terminals 5, 6. The unit 23 accommodates a diode bridge 2, a secondary cell 3, and a transmitter 4. The ignition key device 21 operates in the same manner as the ignition key device 11 shown in FIG. 12.
General ignition key devices of the type described above which are capable of locking and unlocking automobile doors and performing a key function, i.e., turning on and off an ignition switch, are required to be convenient in use. Specifically, the ignition key should easily be inserted into and pulled out of the ignition switch lock, should be resistant to damage or breakage, and should have a suitable size and weight. In addition, the secondary cell 3 must be capable of supplying electrical energy continuously for a long period of time while it is not being connected to a charging circuit.
The ignition key device 1 shown in FIG. 11 is relatively large in size as it has an integrally combined ignition key and remote door lock operating unit. Therefore, the ignition key device 1 may not conveniently be gripped by hand for insertion into or removal from the ignition switch, and hence may not be used with ease.
The ignition key devices 11, 21 shown in FIGS. 12 and 13 are relatively easy to use and free of the above problem of the ignition key device 1 shown in FIG. 11 because the ignition keys 12, 22 are separate from the respective remote door lock operating units 13, 23 and can be gripped by themselves for easy insertion into or removal from the ignition switch lock. However, the remote door lock operating units 13, 23 are still large and heavy and may not conveniently be handled or gripped by hand because of the relatively large and heavy components including at least the secondary cell 3 and the transmitter 4 that are incorporated in the units 13, 23.
Furthermore, the leads 14 which electrically and mechanically interconnect the ignition keys 12, 22 and the respective remote door lock operating units 13, 23 of the ignition key devices 11, 21 have to be covered with insulating layers or protective films, which are relatively expensive, so that the leads 14 are protected from wear, damage or breakage in repeated use.
In each of the ignition key devices 1, 11, 21 shown in FIGS. 11, 12, and 13, the secondary cell 3 is electrically connected to the transmitter 4 at all times. Consequently, while the secondary cell 3 is not being charged, i.e., while the ignition key is not inserted into the ignition switch lock or the ignition key is inserted into the ignition switch lock but the ignition switch is turned off, the secondary cell 3 continuously energizes the transmitter 4. Since the secondary cell 3 continuously consumes the stored electric energy, it cannot operate the ignition key devices 1, 11, 21 continuously for a long period of time after being charged.